GB2200646A - Polymeric polyols - Google Patents

Abstract

Novel polymeric polyols resulting from the reaction of essentially a polyester dialkylester and a polyether polyol may be used in the production of polyurethanes.

Description

POLYMERIC POLYP; This invention relates to polymeric polyols and more particularly to polyols containing both polyether and polyester residues, to the preparation of such polyols and to their use in he production of polyurethanes.

It is well known to manufacture polyurethanes of a cellular or non-cellular, flexible or rigid nature by reacting organic polyisocyanates with polymeric polyols in the presence, where required, of other components such as foaming agents, cross-linking agents, catalysts and surfactants. In general, the polymeric polyols used are either polyesters or polyethers, the properties of the polyurethane being affected accordingly.

In some polyurethane systems, the effect imparted by the polyol is of greater significance than in other systems and a compromise between polyester-derived properties and polyether-derived properties is sometimes desirable. Thus, in elastomer manufacture, polyesters generally provide superior mechanical properties, for example abrasion resistance, whilst polyethers provide better hydrolytic stability and low temperature flexibility. Attempts to provide a compromise by using mixtures of polyethers and polyesters have not, in general, been successful because of the incompatibility of the two types of polymer.

It has now been found that polymeric polyols containing both polyester and polyether residues may be prepared by reacting carboxylic acid ester terminated polyesters with polyether polyols.

Accordingly, the invention provides polymeric polyols having the formula Rl[COOR(OH)m3n (1) wherein R represents the residue remaining after removal of the hydroxyl groups from a polyether polyol, R1 represents the residue remaining after removal of the carboxy end groups from a polyester, m is an integer of at least 1 and n is an integer of from 2 to 4 provided the product of m and n is from 2 to 4.

Preferably, m is 1 or 2.

The polyols of Formula 1 suitably have molecular weights in the range 1000 to 8000. Diols having molecular weights in the range 1000 to 4000 and triols having molecular weights in the range 3000 to 6000 are particularly useful in polyurethane formulations.

The polymeric polyols of the invention may be prepared by reacting a polyester of the formula R1(COOM) (2) n wherein R1 and n have the same meanings as in Formula 1 and M represents a lower alkyl (C14) radical with n moles (per mole of polyester) of a polyether polyol of the formula R(OH)m+i (3) wherein R and m have the same meanings as in Formula 1, the values of m and n being so chosen that their product, the hydroxyl functionality of the polymeric polyol, is from 2 to 4.

The reaction between the polyester and the polyether may be performed at temperatures up to-230 deg. Celsius with removal of lower alkanol.

Polyesters of Formula 2 are well known in the art and may be obtained by reacting one or more glycols, for example ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol or 1,6-hexanediol with an excess, appropriate to the desired molecular weight, of one or more dicarboxylic acid di-lower alkyl esters. Suitable esters include the dimethyl esters of aliphatic and aromatic dicarboxylic acids, for example succinic, glutaric, adipic, sebacic, phthalic and terephthalic acids. It is particularly convenient to use a commercially available mixture of the dimethyl esters of succinic, glutaric and adipic acids, for example a mixture in the approximate weights ratio 1:3:1. If desired, higher functionality components, for example glycerol, trimethylolpropane or pentaerythritol, may be included to introduce a degree of branching into the polyester.

The polyester suitably has a molecular weight in the range from 500 to 4000.

Polyethers of Formula 3 are well known in the art and include the polyether polyols, especially diols and triols, known in the polyurethane art. Thus, the polyether may be polyoxyethylene polyol, a polyoxypropylene polyol, a poly (oxyethylene-oxypropylene) polyol in which the oxyethylene and oxypropylene units are arranged randomly or in blocks, the oxyethylene units comprising from 5 to 75% of the total oxyalkylene units on a molar basis, or a polytetramethylene ether glycol. Mixtures of polyethers may be employed, for example a mixture of a polyoxyethylene polyol and a polyoxypropylene polyol, a mixture of a diol and a triol or a mixture of polyethers differing in hydroxyl number.

Mixtures of polyethers and/or polyesters having different functionalities may be used provided that the average hydroxyl functionality of the product is from 2 to 4.

The polyether suitably has a molecular weight in the range from 200 to 6000.

The polymeric polyols of the invention may be reacted with organic polyisocyanates to form polyurethanes, especially elastomers of a microcellular or non-cellular structure. Suitable polyisocyanates include aromatic diisocyanates, for example 4,4'-diphenylmethane diisocyanate and its mixtures with the 2,4'-isomer. Conventional formulations and techniques may be employed.

The invention is illustrated but not limited by the following Examples.

Example 1 3240 p.b.w. mixed dimethyl esters of adipic, glutaric and succinic acids in a weight ratio of 20:60:20 were charged to a 7.7 1 reactor with 1840 p.b.w. diethylene glycol. The reactor was fitted with an agitator, thermocouple pocket, nitrogen dip tube and glass column packed with 1/4" ceramic Raschig rings. The agitator was started and nitrogen sparging was applied at 62 l/hr.

0.56 p.b.w. tetra butyl o-titanate was added to the reactor contents and heat applied to 185 deg. Celsius maximum. Methanol began to distil at a batch temperature of 160 deg.

Celsius and was collected via a condenser from the column top take-off into a 1 1 measuring cylinder. The batch temperature was allowed to rise to 185 deg. Celsius consistent with maintaining a column tops temperature of 66 deg. Celsius. When the column tops temp. fell to < 50 deg.

Celsius, the N2 sparge rate was increased to 120 l/hr. At a column tops temp of 35-40 deg. Celsius, the nitrogen sparging was reduced to 62 l.hr and the batch cooled to 100-120 deg. Celsius. 1463 p.b.w. methanol had been collected. The reactor contents had a methoxyl content of 4.6 % expressed as % methanol. The time for this stage was 3 hrs.

2730 p.b.w. polypropylene glycol 400 were then charged to the reactor, N2 sparging applied at 62 l/hr and the contents reheated to 230 deg. Celsius (max.). After 7 hrs at 210 deg. Celsius, 170 p.b.w. methanol had been collected. The column was removed and distillation continued directly via condenser from the reactor top; after a further 5 hrs at a N2 sparge rate of 120 l/hr, the product had an analysis of 64.2 mg KOH/g hydroxyl value and a methoxyl content of 0.16% as methanol.

Example 2 3777 p.b.w. mixed dimethyl esters of adipic, glutaric and succinic acids in weight ratio 20;60;20 were charged with 1270 p.b.w. mono-ethylene glycol and reacted as described in Example 1. After the first stage (5 hrs) the methoxyl level was +/- 6 % as methanol. 1575 p.b.w. methanol had distilled. 2330 p.b.w. PPG 400 were added and reacted with the polyester as described in Example 1. Further 125 p.b.w.

of methanol were collected. The final product had a oH-value of 50.8 mg KOH/g and a methoxyl level below < 0.30 % as methanol.

Claims (3)

1. A polymeric polyol having the formula R1 [COOR(OH) mn wherein R represents the residue remaining after removal of the hydroxyl groups from a polyether polyol, R1 represents the residue remaining after removal of the carboxy end groups from a polyester, m is an integer of at least 1 and n is an integer of from 2 to 4, the product of m and n having a value of from 2 to 4.

2. A method for the preparation of a polymeric polyol according to claim 1 which comprises reacting a polyester of the formula R1(COOM) wherein R1 and n have the meanings given in claim 1 and M represents a C14 alkyl radical, with n moles, per mole of polyester, of a polyether polyol of the formula R(OH)m+ wherein R and m have the meanings given in claim 1, the values of m and n being such that the product has a hydroxyl functionality of from 2 to 4.

3. A process for the preparation of a polyurethane which comprises reacting an organic polyisocyanate with a polymeric polyol according to claim 1.